Capsule endoscope devices are small and thus can only incorporate a battery with a limited capacity. Thus, power saving is required for capturing images in a long digestive tract. For example, JP-A-2006-223892 discloses a method for controlling a frame rate to achieve the power saving. In JP-A-2006-223892, at least two images captured in time series are compared with each other to measure the movement of the capsule endoscope device. The imaging frame rate is changed to be low when the movement of the capsule endoscope device is determined to be relatively slow, and is changed to be high when the movement of the capsule endoscope device is determined to be relatively fast.